Abstract: This study aims to investigate whether the addition of high-inhibition water can enhance the inhibitory effect of MgCl₂ inhibitor on coal, and to explore the role of high-inhibition water in improving the effectiveness of fire prevention and extinguishing in coal mines. Using thermogravimetric analysis (TG-DSC) and temperature-programmed experiments, a systematic comparison was made among raw coal, MgCl₂-inhibited coal samples, and coal samples treated with high-inhibition water compounded MgCl₂ inhibitor, in terms of characteristic temperatures, activation energy, gas product generation, and oxygen consumption characteristics during pyrolysis and combustion. The results show that the high-inhibition water compounded MgCl₂ inhibitor can significantly increase characteristic temperature points such as the critical temperature, ignition temperature, and burnout temperature, thus delaying the spontaneous combustion process of coal. Meanwhile, it effectively inhibits the generation rates of key gases such as CO, CO₂ and C₂H₄, and remarkably reduces the oxygen consumption rate of the coal sample, exhibiting the most pronounced inhibitory effect. It is concluded that the addition of high-inhibition water further enhances the inhibitory effect of the inhibitor, retards the combustion reaction process, and reduces the spontaneous combustion tendency, demonstrating superior inhibitory performance compared to the inhibitor used alone.